Default form.csrf_protection.enabled to csrf_protection.enabled
bug #9673 Fixed BC break in csrf protection (WouterJ)

This PR was merged into the 2.4 branch.

Discussion
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Fixed BC break in csrf protection

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9429
| License       | MIT
| Doc PR        | n/a

Commits
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d00954a Default form.csrf_protection.enabled to csrf_protection.enabled